Impact and shear resistant plastics 1

[CADShark]

I have an application in which I'm molding a plastic handle around a screw with three holes thru the center of it.

The problem is finding a plastic that has BOTH high impact resistance and shear strength.

I've been able to find plastics that work in both areas, but to no avail they are differnt materials. I've tried ABS, Nylon, Verton, Lexan, Zytel, Isoplast 101.

I would love to mix them together and get what I would call a "Superplastic" but that will never happen.

Any ideas?

CADShark

 

[patprimmer]

I'm surprised that the nylon won't do it. Zytel is a brand name of nylon.

How did the nylon fail.

Can you post a photo or drawing, as slight modifications to the design might fix it.

if you can't post it here, can you e-mail them to me at patprimmer@swiftdsl.com.au

nylons mechanical properties are dramatically affected by moisture conditioning.

Nylon is extensivly used in applications that require both shear and impact, like automotive internal engine parts, yacht deck fittings, yachting winch handles, plastic hammer faces, etc etc

Regards
pat

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[CADShark]

Pat,

The nylon work great under shear strength, as well as the Zytel. They didn't shear until about 150-170 in/lbs of torque.

We've figured that we need more area to distribute the shear strength. Right now we have three 1/8" diameter holes going thru the screw that is overmolded. If i can increase the diameter to 5/32" I can increase the area by 55 percent.

The way we test impact is by dropping a 6 pound weight on a certain point of the handle and recording the results.

Thanks